Since time immemorial and throughout Roman and Christian empire expansion between the 2nd Century BC and the 12th Century CE into Germania, many Germanic and Celtic Tribes wore feathers (not horns) of sacred and revered birds into battle, and these feathers symbolized their prowess, honor, and bravery.
These feathers were bestowed upon warriors by chiefs or spiritual elders within the tribe, or by other tribes, bearing similarities to the use of feathers for indigenous peoples of North America. Eagle feathers were used by Germanian Tribes, but the eagle became a symbol of Rome, and with the expansion and atrocities committed against the Tribes by Rome, the veneration of the eagle faded.
Feathers were sacred items, and the misuse and misrepresentation of earning them was a severe crime in “Barbarian Law”, and would often be considered treasonous, punishable by death.
The use of these feathers persisted until the nearly complete Christianization of the Germanic Tribes, and the feudal system replaced the indigenous tribal cultures, and they became “white”.
Also, despite what you may see in popular media, all Germanic Tribes focused on extensive personal hygiene and grooming, and were rarely seen dirty or unkempt. One would be an outcast if they did not bathe or dress impeccably.
The portrayal of the indigenous Germanic people as dirty and filthy added to the fear being spread by the Romans, and later, Christians. Rome and the Church were clean and pure, while the evildoing pagan Barbarian savages lived in filth and in the woods like animals, and were a threat to all that is pure and just.
The Northern Tribes were especially known for their hygiene, and some stories remain from the British Isles between 793 and 1066, considered the Viking Age, about how the women there looked forward to raiding season, because the men coming were so much cleaner than the men of the isles.
This tactic was also used in American expansionism, and is referenced in its earliest foundational documents, calling the indigenous people of the land, “Merciless Indian Savages” in the Declaration of Independence.
One Germanic tribe is still honored for their hairstyle: The Suebenknoten, the Suebian Knot. The more elaborate the knot, the higher status one has Although this hairstyle is named for the Suebi, also sometimes called the Suevi, it, and similar hairstyles are used by a majority of the tribes.
These knots and hairstyles kept hair off the back of the head, and orderly. Sometimes, they were adorned with beads, fabric, and feathers. Hair on the back of ones head in battle could be used against you, it makes a great handle to control your opponent with, like reins.
Modern American football players, with long hair out the back of their helmets, would be laughed at in Germanic combat.
Having your long hair down when at home with family or in non-combat situations was acceptable, but it must be combed and kempt. Grooming tools were common among the indigemous Germanian people, combs, picks, tweezers, and even ear spoons (like a reusable Q-Tip) are often found in burial sites.
Ceremony and ritual often accompanied the grooming of hair before combat, is was often done by the wives, partners, slaves, children, or spiritual leaders of the tribe.
Beards were also often groomed and adorned before battle or ceremony.